1. Field of the Invention
The present invention relates to a manufacturing apparatus, and more particularly, to an apparatus for manufacturing a liquid crystal display suitable for a large-sized liquid crystal display.
2. Discussion of the Related Art
In general, recent developments in the information communication field have increased demand for various types of displays devices. In response to this demand, various flat panel type displays such as liquid crystal display (LCD), plasma display panel (PDP), electro-luminescent display (ELD), and vacuum fluorescent display (VFD) have been developed to replace conventional cathode ray tube (CRT) devices. In particular, LCD devices have been used because of their high resolution, light weight, thin profile, and low power consumption. In addition, LCD devices have been implemented in mobile devices such as monitors for notebook computers. Furthermore, LCD devices have been developed for monitors of computer and television to receive and display broadcasting signals.
Accordingly, efforts to improve image quality of LCD devices contrast with the benefits of their high resolution, light weight, thin profile, and low power consumption. In order to incorporate LCD devices as a general image display, image quality such as fineness, brightness, large-sized area, for example, must be realized.
A plurality of gate lines are formed along one direction at fixed intervals on the first glass substrate (TFT array substrate), and a plurality of data lines are formed along a second direction perpendicular to one direction of the plurality of gate lines, thereby defining a plurality of pixel regions. Then, a plurality of pixel electrodes are formed in a matrix arrangement at the pixel regions, and a plurality of thin film transistors (TFT) are formed at the pixel regions. Accordingly, the plurality of thin film transistors are switched by signals transmitted along the gate lines and transfer signals transmitted along the data lines to each pixel electrode. In order to prevent light leakage, black matrix films are formed on the second glass substrate (color filter substrate) except at regions of the second glass substrate that correspond to the pixel regions of the first glass substrate.
A process for manufacturing an LCD device using a TFT substrate and a color filter substrate will be described with reference to a manufacturing apparatus according to the related art.
The process for manufacturing an LCD device according to the related art includes steps of forming a sealant pattern on one of a first and second substrate to form an injection inlet, bonding the first and second substrates to each other within a vacuum processing chamber, and injecting liquid crystal material through the injection inlet. In another process of manufacturing an LCD device according to the related art, a liquid crystal dropping method, which is disclosed in Japanese Patent Application No. 11-089612 and 11-172903, includes steps of dropping liquid crystal material on a first substrate, arranging a second substrate over the first substrate, and moving the first and second substrates, thereby bonding the first and second substrates to each other. Compared to the liquid crystal injection method, the liquid crystal dropping method is advantageous in that various steps such as, formation of a liquid crystal material injection inlet, injection of the liquid crystal material, and sealing of the injection inlet are unnecessary since the liquid crystal material is predisposed on the first substrate.
FIGS. 1 and 2 show cross sectional views of a substrate bonding device using the liquid crystal dropping method according to the related art. In FIG. 1, the substrate bonding device includes a frame 10, an upper stage 21, a lower stage 22, a sealant dispenser (not shown), a liquid crystal material dispensor 30, a processing chamber includes an upper chamber unit 31 and a lower chamber unit 32, a chamber moving system 40, and a stage moving system 50. The chamber moving system 40 includes a driving motor driven to selectively move the lower chamber unit 32 to a location at which the bonding process is carried out, or to a location at which outflow of the sealant occurs and dropping of the liquid crystal material. The stage moving system 50 includes another driving motor driven to selectively move the upper stage 21 along a vertical direction perpendicular to the upper and lower stages 21 and 22. A receiving system temporarily receives a substrate 52 at opposite diagonal portions of the substrate 52. The receiving system is attached to the upper stage 21, and includes a rotational axis 61 provided to extend from an exterior of the upper chamber unit 31 to an interior of the upper chamber unit 31, a rotational actuator 63 fixed to the exterior of the upper chamber unit 31 at one end of the rotational axis 61 and driven to selectively rotate the rotational axis 61, an elevating actuator 64 selectively elevating the rotational actuator 63, and a receiving plate 62 provided at the other end of the rotational axis 61 to form a single body with the rotational axis 61, thereby selectively supporting opposite edge portions of the substrate 52.
A process of manufacturing a liquid crystal display device using the substrate assembly device according to the prior art follows. First, a second substrate 52 is loaded upon the upper stage 21, and a first substrate 51 is loaded upon the lower stage 22. Then, the lower chamber unit 32 having the lower stage 22 is moved to a processing location (S1) by the chamber moving system 40 for sealant dispensing and liquid crystal material dispensing. Subsequently, the lower chamber unit 32 is moved to a processing location (S2) for substrate bonding by the chamber moving system 40. Thereafter, the upper and lower chamber units 31 and 32 are assembled together by the chamber moving system 40 to form a vacuum tight seal, and a pressure in the chamber is reduced by a vacuum generating system (not shown). The elevating actuator 64 is driven to move the rotational axis 61 toward a lower part of the upper stage 21, and at the same time the rotational actuator 63 is driven to rotate the rotational axis 61 so that the receiving plate 62 is positioned at both edges of the second substrate 52 fixed to the upper stage 21.
FIGS. 2 and 3 show a perspective view of an operational state of a receiving system of a substrate assembly device according to a prior art. In FIGS. 2 and 3, when the stage moving system 50 moves the upper stage 21 downward in close corresponding to a height at which the receiving plate 62 is positioned.
When a vacuum state is achieved inside the assembled chamber, the second substrate 52 may fall from the upper stage 21 since the vacuum pressure within the chamber is larger than the vacuum force affixing the second substrate 52 to the upper stages 21. Accordingly, before the desired vacuum pressure within the chamber is achieved, it is necessary to keep the second substrate 52 temporarily affixed to the upper stage 21. Once the desired vacuum pressure within the chamber part is attained, the second substrate 52 is affixed to the upper stage 21 by application an electrostatic force to the upper stage 21. Accordingly, the receiving plates 62 and rotational axis 61 are returned to original standby locations by driving the rotational actuator 63 of the receiving system and the elevating actuator 64.
Then, the upper stage 21 is moved downwardly by the stage moving system 50 at the above-mentioned vacuum state so as to closely fasten the second substrate 52 fixed to the upper stage 21 to the first substrate 51 fixed to the lower stage 22. Further, the process for bonding the respective substrates to each other is carried out through a continuous pressurization, thereby completing the manufacture of the LCD device.
However, the substrate assembly device according to the prior art is problematic. First, the substrate assembly device according the prior art fails to provide a subsidiary system or device for stable loading of the substrate at the lower stage or unloading the bonded substrates from the lower stage, thereby creating a high probability that damage to the substrate(s) may occur during the loading/unloading process. Specifically, the bonded substrates may adhere to a upper surface of the lower stage during the bonding process. Second, when the bonded substrates are unloaded, central or circumferential portions of the bonded substrates will be free of droop. Specifically, considering that the size of LCD devices are increasing to meet demand, preventing droop during unloading of the bonded substrates is extremely important and necessary.